The present invention relates to a process and a device for improving the stiffness of a substantially parallelepipedal container made of a synthetic material, the said container being obtained by shaping and weldings from a film which is made of the said synthetic material and is to enclose the liquid to be packaged.
It also relates to containers obtained in this way.
Processes and devices of this type are already generally known per se.
They have, for example, but not in a limiting way, been the subject of patents and/or patent applications filed by the Applicant.
Thus in French Patent 2,554,785 a process has been proposed for attaching a stiff or semi-stiff handle to a carton made of a flexible synthetic material. This process is still relatively complex to implement because of compatibility problems between the different materials used. Moreover the stiffening is strictly linked to the grip and the said stiffening is not uniformly ensured over all the surfaces.
In French Patent 2,577,893 filed by the Applicant it has been proposed to equip a flexible bag with rigid stiffening and stabilization means, specifically ribs formed from the material of the film. The implementation of this process in industry remains difficult.
In French Patent Application 2,611,163, also filed by the Applicant, it is envisaged to shape a bag filled with thc liquid to be packaged and then to enclose the said bag and to shape it with a sleeve made of a synthetic material which can be drawn, said sleeve being cold-formed by jaws capable of translational movement and at a distance from each other. This device is satisfactory but can be improved as regards the sequence of operations since in this case the stiffening has an effect on the bag which is already filled, this being a source of potential problems for the container of the said bag.